xref: /netbsd-src/games/tetris/input.c (revision d710132b4b8ce7f7cccaaf660cb16aa16b4077a0)
1 /*	$NetBSD: input.c,v 1.8 2002/12/29 15:12:17 kristerw Exp $	*/
2 
3 /*-
4  * Copyright (c) 1992, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * Chris Torek and Darren F. Provine.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by the University of
21  *	California, Berkeley and its contributors.
22  * 4. Neither the name of the University nor the names of its contributors
23  *    may be used to endorse or promote products derived from this software
24  *    without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  *
38  *	@(#)input.c	8.1 (Berkeley) 5/31/93
39  */
40 
41 /*
42  * Tetris input.
43  */
44 
45 #include <sys/types.h>
46 #include <sys/time.h>
47 #include <sys/poll.h>
48 
49 #include <errno.h>
50 #include <unistd.h>
51 
52 #include "input.h"
53 #include "tetris.h"
54 
55 /* return true iff the given timeval is positive */
56 #define	TV_POS(tv) \
57 	((tv)->tv_sec > 0 || ((tv)->tv_sec == 0 && (tv)->tv_usec > 0))
58 
59 /* subtract timeval `sub' from `res' */
60 #define	TV_SUB(res, sub) \
61 	(res)->tv_sec -= (sub)->tv_sec; \
62 	(res)->tv_usec -= (sub)->tv_usec; \
63 	if ((res)->tv_usec < 0) { \
64 		(res)->tv_usec += 1000000; \
65 		(res)->tv_sec--; \
66 	}
67 
68 /*
69  * Do a `read wait': poll for reading from stdin, with timeout *tvp.
70  * On return, modify *tvp to reflect the amount of time spent waiting.
71  * It will be positive only if input appeared before the time ran out;
72  * otherwise it will be zero or perhaps negative.
73  *
74  * If tvp is nil, wait forever, but return if poll is interrupted.
75  *
76  * Return 0 => no input, 1 => can read() from stdin
77  */
78 int
79 rwait(tvp)
80 	struct timeval *tvp;
81 {
82 	struct pollfd set[1];
83 	struct timeval starttv, endtv;
84 	int timeout;
85 #define	NILTZ ((struct timezone *)0)
86 
87 	if (tvp) {
88 		(void) gettimeofday(&starttv, NILTZ);
89 		endtv = *tvp;
90 		timeout = tvp->tv_sec * 1000 + tvp->tv_usec / 1000;
91 	} else
92 		timeout = INFTIM;
93 again:
94 	set[0].fd = STDIN_FILENO;
95 	set[0].events = POLLIN;
96 	switch (poll(set, 1, timeout)) {
97 
98 	case -1:
99 		if (tvp == 0)
100 			return (-1);
101 		if (errno == EINTR)
102 			goto again;
103 		stop("poll failed, help");
104 		/* NOTREACHED */
105 
106 	case 0:	/* timed out */
107 		tvp->tv_sec = 0;
108 		tvp->tv_usec = 0;
109 		return (0);
110 	}
111 	if (tvp) {
112 		/* since there is input, we may not have timed out */
113 		(void) gettimeofday(&endtv, NILTZ);
114 		TV_SUB(&endtv, &starttv);
115 		TV_SUB(tvp, &endtv);	/* adjust *tvp by elapsed time */
116 	}
117 	return (1);
118 }
119 
120 /*
121  * `sleep' for the current turn time.
122  * Eat any input that might be available.
123  */
124 void
125 tsleep()
126 {
127 	struct timeval tv;
128 	char c;
129 
130 	tv.tv_sec = 0;
131 	tv.tv_usec = fallrate;
132 	while (TV_POS(&tv))
133 		if (rwait(&tv) && read(0, &c, 1) != 1)
134 			break;
135 }
136 
137 /*
138  * getchar with timeout.
139  */
140 int
141 tgetchar()
142 {
143 	static struct timeval timeleft;
144 	char c;
145 
146 	/*
147 	 * Reset timeleft to fallrate whenever it is not positive.
148 	 * In any case, wait to see if there is any input.  If so,
149 	 * take it, and update timeleft so that the next call to
150 	 * tgetchar() will not wait as long.  If there is no input,
151 	 * make timeleft zero or negative, and return -1.
152 	 *
153 	 * Most of the hard work is done by rwait().
154 	 */
155 	if (!TV_POS(&timeleft)) {
156 		faster();	/* go faster */
157 		timeleft.tv_sec = 0;
158 		timeleft.tv_usec = fallrate;
159 	}
160 	if (!rwait(&timeleft))
161 		return (-1);
162 	if (read(0, &c, 1) != 1)
163 		stop("end of file, help");
164 	return ((int)(unsigned char)c);
165 }
166